1. Field of the Invention
The present invention relates to device and method for controlling a drain motor in a fully automatic washing machine, and more particularly, to device and method for controlling a drain motor, in which a drain valve is driven with reference to a position of drain valve, for optimal control of the drain motor.
2. Background of the Invention
Though the dirt on clothes is removed by chemical reaction of detergent in the washing water once the clothes is put into the washing water, the washing machine for removing dirt stuck on clothes exerts mechanical action, such as friction or vibration, to the clothes for accelerating removal of the dirt, because the removal of dirt from the clothes only by the action of the detergent takes a long time.
In operating the washing machine, first, a washing mode is conducted, in which a quantity of laundry, such as clothes, introduced into a washing tub is detected to determine the quantity of laundry, water flow, detergent, and a total washing time period are set according to the quantity of laundry, and the pulsator is pulsated according to the total washing time period, to circulate the washing water for removing the dirt on the clothes through friction with the laundry. Then, upon completion of the washing mode, a rinsing mode is conducted, in which dirt water in the washing tub is discharged, fresh water is supplied to the washing tub, rinsing is carried out for a preset time set in the system already. Upon completion of the rinsing mode, a spinning mode is conducted, in which the water in the washing tub is discharged, and the induction motor is rotated at a preset high speed, for removing water from the laundry by centrifugal force. During the washing and rinsing modes, a drain vale is held closed, and during the spinning mode, the drain valve is held open.
FIG. 1 illustrates a bottom view showing a related art drain motor and drain valve.
During the washing and rinsing modes of the washing machine, the drain motor 30 is held turned off, and the drain valve 33 is kept closed, for not draining the washing water. In this state, a brake lever 32 interlocked with a connection link 31 transmitting an action of the drain motor 30 to the drain valve 33 is disposed at a position where a brake band (not shown) fixes a drain shaft (not shown) according to a position of the connection link, and since a fore end of a clutch lever 12 is to pull an end of a clutch spring 16, to bring the spring into a state in which a diameter of the clutch spring 16 becomes greater than an original diameter, that releases the clutch 20, the washing shaft connected to the pulsator is free from the spinning shaft connected to the washing tub. In the spinning mode, the drain motor 30 is put into operation, to retract the connection link 31 backward, and to open the drain valve 33, leaving the washing water in a state to be drained, and on the same time, the retraction of the connection link 31 moves the brake lever 32 also to release the spinning shaft from the brake band, and the backward movement of the brake band pushes a connecting screw, to release the clutch lever 12 having the connecting screw fastened thereto to restore the clutch spring 16 into an original state, thereby permitting the washing shaft and the spinning shaft engaged. There are washing machines provided with two step drain valve and drain motor as the case requires. That is, during draining, a voltage is provided to the drain motor 30, to drive the brake lever 32 of the clutch 20 and the drain valve 33 on the same time, and upon finish of the draining, the voltage to the drain motor 30 is cut off, to restore the drain valve 33 automatically by the clutch spring 16 attached to the drain valve 33. However, the large sized motor coming from a high power required for driving the brake lever 32 and the drain valve 33 on the same time in draining in the related art costs high and occupies a large space.
Accordingly, the present invention is directed to device and method for controlling a drain motor that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide device and method for controlling a drain motor, in which a drain motor is adapted to be controlled in an optimal condition to permit a small sized motor, for reducing cost and a space occupied by the drain motor.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the device for controlling a drain motor includes a drain motor cam connected to a shaft of the drain motor having a detecting point for detecting a bottom dead center of a drain valve marked on one region of a circumference thereof, a switching unit for detecting a position of detecting point of the drain motor cam when the drain motor cam is rotated to provide a position detecting signal, and a microcomputer for receiving the position detecting signal from the switching unit, to identify a position of the drain valve, and controlling operation of the drain motor according to a result of the identification.
In other aspect of the present invention, there is provided a method for controlling a drain motor, including the steps of (1) initializing the drain motor for detecting a bottom dead center of a drain valve, (2) measuring a time period while operating the drain motor once the bottom dead center of the drain valve is detected, (3) stopping the drain motor and carrying out drain operation if the time period measured in the step (2) is the same with a preset motor stop time period, and (4) returning the drain valve to an original state to the bottom dead center of the drain valve upon completion of the rain operation in the step (3).
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.